A. Given a = 5, b = 1, x = 10, and y = 5, create a program that outputs the result of the formula f = (a b)(x y) using a single printf() function. B. Create a program that uses the same formula above to output the result; this time, however, prompt the user for the values a, b, x, and y. Use appropriate variable names and naming conventions. C. Create a program that prompts a user for her name. Store the user’s name using the scanf() function and return a greeting back to the user using her name. D. Create a new program that prompts a user for numbers and determines total revenue using the following formula: Total Revenue = Price * Quantity. E. Build a new program that prompts a user for data and determines a commission using the following formula: Commission = Rate * (Sales Price – Cost).